Rapid identification of microbial pathogens has long been an important goal of diagnostic technology. In addition to identifying the pathogenic species, the clinician must now affirm the potential efficacy of standard antimicrobial treatments early in the treatment of each case. Delays and erroneous results associated with conventional diagnostic tests frequently lead to the administration of ineffective treatments, which in turn lead to complications, added costs, and poor outcomes.
Tuberculosis (TB) kills 3,000,000 people in the world every year, more than AIDS, malaria, and other tropical diseases combined. One third of the world's population is infected with tuberculosis and it represents more than a quarter of the world's preventable deaths. The responsible mycobacteria are Gram-positive (no outer cell membrane), non-motile, pleomorphic rods, related to Actinomyces.
Organisms of the Mycobacterium tuberculosis (MTB) complex are responsible for the significant TB-associated morbidity and mortality observed in humans. The TB complex consists of the following species: M. tuberculosis, M. bovis, M. bovis BCG, M. africanum, M. microti, and M. canetti. M. tuberculosis is the most common MTB complex pathogen isolated in humans. M. bovis BCG may be transmitted from infected animals to humans, M. africanum causes pulmonary tuberculosis in tropical Africa and M. microti primarily infects animals.
Tuberculosis is highly contagious, therefore rapid diagnosis of the disease is important. Classical methods for identification of mycobacteria rely on staining specimens for acid fast bacilli followed by culture and biochemical testing. These cumbersome techniques render the identification and quantification of MTB complex pathogen very inefficient.
Therefore, although there are reports of PCR-based tests for diagnosis of TB, there is a continuing need for highly sensitive assays to rapidly detect the organisms causing TB. See Park et al., Arch Pathol Lab Med, Vol. 127, March 2003, pp. 326-330; Brisson-Noel et al., Lancet 1989; 2:1069-1071; Beige et al., J. Clin. Microbiol. 1995; 33:90-95; Perosio et al., Am. J. Clin. Pathol. 1993; 100:643-647; Hardman et al., Am. J. Clin. Pathol. 1996; 106:384-389; Salian et al., Am. J. Respir. Crit. Care Med. 1998; 158:1150-1155; Vago et al., Am. J. Clin. Pathol. 1998; 109:411-415.
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